Air-oxidative hair dye compositions using a melanin precursor such as indoles or indolines have conventionally been known (refer to, for example, Patent Documents 1 to 3). These hair dyes however require use of a coupler in combination with a melanin precursor in order to change the color of hair dyed with them.    Patent Document 1 JP-B-8-32618    Patent Document 2 JP-A-2003-55175    Patent Document 3 JP-A-2002-322038